A5070765152- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Astro and Planetary Science
- High-pressure geophysics and materials
- X-ray Spectroscopy and Fluorescence Analysis
- Galaxies: Formation, Evolution, Phenomena
- Adaptive optics and wavefront sensing
- Advanced X-ray Imaging Techniques
- Solar and Space Plasma Dynamics
- Calibration and Measurement Techniques
- Atomic and Molecular Physics
- Nuclear Physics and Applications
- Geophysics and Gravity Measurements
- Particle Accelerators and Free-Electron Lasers
- Particle Detector Development and Performance
- Mechanics and Biomechanics Studies
- Superconducting Materials and Applications
- Geophysics and Sensor Technology
- Scientific Measurement and Uncertainty Evaluation
Massachusetts Institute of Technology
2012-2024
Vassar College
2005-2024
Kavli Energy NanoScience Institute
2017-2021
Moscow Institute of Thermal Technology
2000-2020
Kavli Institute for Particle Astrophysics and Cosmology
2010-2020
Observatoire astronomique de Strasbourg
2010
European Space Astronomy Centre
2010
California Institute of Technology
2010
Roma Tre University
2010
Osservatorio Astronomico di Palermo
2010
We present high-resolution X-ray spectra of the X-ray-bright classical T Tauri star, TW Hydrae, covering wavelength range 1.5-25 Å. The differential emission measure derived from fluxes temperature-sensitive lines shows a plasma with sharply peaked temperature distribution, peaking at log = 6.5. Abundance anomalies are apparent, iron very deficient relative to oxygen, while neon is enhanced oxygen. Density-sensitive line ratios Ne IX and O VII indicate densities near ne 13. A flare rapid (~1...
Details of the design, fabrication, ground and flight calibration High Energy Transmission Grating, HETG, on Chandra X-ray Observatory are presented after five years experience. Specifics include theory phased transmission gratings as applied to Rowland design spectrometer, details grating fabrication techniques, results testing HETG. For nearly six HETG has operated essentially designed, although it some subtle effects.
The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with High-Energy Transmission Grating (HETG) readout by Advanced CCD Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at resolution comparable to that best ground-based visible-light observations. HETG-ACIS-S reveal, for first time, an inner ring within torus, suggestion hollow-tube knots along (perhaps) inward extension jet. Although...
The time-averaged 30 ks Chandra HETGS observation of the micro-quasar GRS 1915+105 in low hard state reveals for first time this source neutral K absorption edges from Fe, Si, Mg, & S. Ionized resonance H-, and He-like Fe (XXV, XXVI), Ca XX possibly emission Kalpha ionized XXV (forbidden, or component a P-Cygni profile) are also seen. We report tentative detection astrophysical signature XAFS photoelectric edge Si (and Mg), attributed to material grains. large column densities measured...
MARX is a portable ray-trace program that was originally developed to simulate event data from the trans- mission grating spectrometers on-board Chandra X-ray Observatory (CXO). has since evolved include detailed models of all CXO science instruments and been further modified serve as an simulator for future observatory design concepts. We first review number applications demonstrate roles such could play throughout life mission, including its calibration, production input products...
The Great Nebula in Carina provides an exceptional view into the violent massive star formation and feedback that typifies giant HII regions starburst galaxies. We have mapped star-forming complex X-rays, using archival Chandra data a mosaic of 20 new 60ks pointings X-ray Observatory's Advanced CCD Imaging Spectrometer, as testbed for understanding recent ongoing to probe Carina's bright diffuse emission. This study has yielded catalog properties >14,000 point sources; >9800 them...
High-resolution spectra of the active binary Capella (G8 III + G1 III) covering energy range 0.4-8.0 keV (1.5-30 Å) show a large number emission lines, demonstrating performance High-Energy Transmission Grating Spectrometer. A preliminary application plasma diagnostics provides information on coronal temperatures and densities. Lines arising from different elements in ionization states indicate that has with broad temperatures, log T = 6.3 to 7.2, generally consistent recent results...
We present detailed evidence for a warm absorber in the Seyfert 1 galaxy MCG -6-30-15 and dispute earlier claims relativistic O line emission. The High-Energy Transmission Grating spectra show numerous narrow, unresolved (FWHM ≲ 200 km s-1) absorption lines from wide range of ionization states N, O, Mg, Ne, Si, S, Ar, Fe. VII edge 1s2-1snp resonance series to n = 9 are clearly detected at rest active galactic nucleus frame. attribute previous reports an apparently highly redshifted (n > 5)...
We present observations of SS 433 using the Chandra High Energy Transmission Grating Spectrometer. Many emission lines highly ionized elements are detected with relativistic blue and red Doppler shifts. The measurably broadened to 1700 km s-1 (FWHM), widths do not depend significantly on characteristic temperature, suggesting that occurs in a freely expanding region constant collimation an opening angle 123 ± 006. blueshifts from low-temperature gas same as those high-temperature within...
We present high-resolution spectroscopy of the oxygen K-shell interstellar absorption edge in seven X-ray binaries using High Energy Transmission Grating Spectrometer (HETGS) onboard Chandra X-Ray Observatory. Using brightest sources as templates, we found a best-fit model two edges and five Gaussian lines. All these features can be explained by recent predictions from neutral ionized atomic oxygen. identify Kα Kβ lines oxygen, well S = 3/2 edge. The expected 1/2 is not detected data because...
In this paper we present a comprehensive survey of 41 X-ray binaries (10 HMXBs and 31 LMXBs) with Chandra, specific emphasis on the Fe K region narrow Kalpha line, at highest resolution possible. We find that: a) The line is always centered 1.9387 +- 0.0016 Angstroms, compatible I up to X; detect no shifts higher ionization states nor any difference between LMXBs. b) very narrow, FWHM < 5 mAngstroms, which means that reprocessing material not rotating high speeds. c) fluorescence in all HMXB...
The Chandra Transmission Grating Data Archive and Catalog (TGCat) provides easy access to analysis-ready products, specifically, high-resolution X-ray count spectra their corresponding calibrations. web interface makes it find observations of a particular object, type or observation; quickly assess the quality potential usefulness from pre-computed summary plots; customize view with an interactive plotter, optionally combining over multiple orders observations. responses can be downloaded as...
We further investigate subpixel event repositioning (SER) algorithms in application to Chandra X-Ray Observatory (Chandra) CCD imaging. SER have been applied backside-illuminated (BI) Advanced Imaging Spectrometer (ACIS) devices and demonstrate spatial resolution improvements ACIS observations. Here a new algorithm that is charge split-dependent added the family. describe of frontside-illuminated (FI) devices. The results for FI CCDs are compared with those obtained from techniques BI data....
We observed the Galactic black hole Cygnus X-1 with Chandra High Energy Transmission Grating Spectrometer for 30 kiloseconds on 4 January, 2001. The source was in an intermediate state, a flux that approximately twice commonly its persistent low/hard state. Our best-fit model X-ray spectrum includes narrow Gaussian emission line (E = 6.415 +/- 0.007 keV, FWHM 80 (+28, -19) eV, W 16 (+3, -2) eV) and broad 5.82 (+0.06, -0.07) 1.9 (+0.5, -0.3) 140 (+70, -40) components, smeared edge at 7.3 0.2...
We present high-resolution spectroscopy of the neon K-shell and iron L-shell interstellar absorption edges in nine X-ray binaries using High Energy Transmission Grating Spectrometer (HETGS) onboard Chandra Observatory. found that is well fit by an experimental determination cross-section for metallic iron, although with a slight wavelength shift ~20 mA. The edge region best model includes neutral three Gaussian lines. identify these lines as due to 1s-2p transitions from Ne II, III, IX. As...
We present analyses of a 50 ks observation the supergiant X-ray binary system Cygnus X-1 (Cyg X-1)/HDE226868 taken with Chandra High Energy Transmission Grating Spectrometer (HETGS). Cyg was in its spectrally hard state and performed during superior conjunction black hole, allowing for spectroscopic analysis accreted stellar wind along line sight. A significant part covers dips as commonly observed at this orbital phase, however, here we analyze only high count rate nondip spectrum. The full...
Because supernova remnants are short lived, studies of neutron star X-ray binaries within probe the earliest stages in life accreting stars. However, such objects exceedingly rare: none were known to exist our Galaxy. We report discovery natal remnant Circinus X-1, which places an upper limit t < 4, 600 years on its age, making it youngest binary and a unique tool study accretion, evolution, core collapse supernovae. This is based deep 2009 Chandra observation new radio observations X-1. X-1...
Recent work on jets and disk winds in low-mass X-ray binaries (LMXBs) suggests that they are to a large extent mutually exclusive, with observed spectrally hard states soft states. In this paper we use existing literature the luminous neutron star (NS) LMXB GX 13+1, combination archival Rossi Timing Explorer data, show source is likely able produce simultaneously. We find occur same location source's track its color-color diagram. A further study of other LMXBs reveals behavior more common,...
Arcus will be proposed to the NASA Explorer program as a free-flying satellite mission that enable high-resolution soft X-ray spectroscopy (8-50) with unprecedented sensitivity – effective areas of >500 sq cm and spectral resolution >2500. The key science goals are (1) determine how baryons cycle in out galaxies by measuring effects structure formation imprinted upon hot gas is predicted lie extended halos around galaxies, groups, clusters, (2) black holes influence their surroundings...
4U 0114+65 is a high-mass X-ray binary system formed by the luminous supergiant B1Ia, known as V{*} V662 Cas, and one of slowest rotating neutron stars (NS) with spin period about 2.6 hours. This fact provides rare opportunity to study interesting details accretion within each individual pulse compact object. In this paper, we analyze 200 ks Chandra grating data, divided into 9 uninterrupted observations around orbit. The changes in circumstellar absorption column through orbit suggest an...
Abstract Cosmic dust plays a crucial role in the evolution of galaxies, significantly influencing star formation and interstellar medium. However, active galactic nuclei (AGNs), origin remain poorly understood. High-resolution X-ray spectroscopy is powerful tool for probing properties AGN. NGC 6860, an bright type-1 quasar, ideal target investigating connection between winds It exhibits reddening absorption by both winds. By modeling high-resolution spectra from XMM-Newton Chandra...
Chandra observations of the Crab-like supernova remnant G21.5-0.9 reveal a compact central core and spectral variations indicative synchrotron burn-off higher energy electrons in inner nebula. The is slightly extended, perhaps indicating presence an wind-shock nebula surrounding pulsar. No pulsations are observed from region, yielding upper limit ~40% for pulsed fraction. A faint outer shell may be first evidence expanding ejecta blast wave formed initial explosion, composite nature G21.5-0.9.
We have obtained high-resolution X-ray spectra of the coronally active binary II Pegasi (HD 224085), covering wavelength range 1.5-25 Å. For first half our 44 ks observation, source was in a quiescent state with constant flux, after which it flared, reaching twice flux 12 ks, then decreased. analyze emission-line spectrum and continuum during flaring states. The differential emission measure derived from lines fluxes shows hot corona continuous distribution temperature. During nonflare...
We observed the black hole candidate Cyg X-1 for 15 ks with High-Energy Transmission Grating Spectrometer aboard Chandra X-Ray Observatory. The source was during a period of intense flaring activity, so it about factor 2.5 brighter than usual, 0.5-10 keV (1-24 Å) luminosity 1.6 × 1037 ergs s-1 (at distance kpc). spectrum shows prominent absorption edges, some which have complicated substructure. use most recent results from laboratory measurements and calculations to model substructure...
We report on a 39 ks observation of the 7.7 s low-mass X-ray binary pulsar 4U 1626-67 with High Energy Transmission Grating Spectrometer (HETGS) Chandra X-Ray Observatory. This ultracompact system consists disk-accreting magnetic neutron star and very low mass, hydrogen-depleted companion in 42 minute binary. have resolved previously reported Ne/O emission line complex near 1 keV into Doppler pairs broadened (≈2500 km s-1 FWHM) lines from highly ionized Ne O. In most cases, blue red...